There are considered to be primarily two snuffs - one made from the Anadenanthera peregrine tree called yopo or cohoba, and the other made from virola trees, called epená. Despite confusion the two snuffs are botanically unrelated.
Yopo today is found in use in the Orinoco region of South America, although there was evidently much pre-conquest trade in yopo so that its former range extended into the West Indies and Argentina. The seeds or beans are toasted and then mositened into a paste with lime added to assist with the potentiation. The resulting mass is then pulverized into a grey-greenish powder, which is then blown up one's nose, in shamanic ritual.
Epená, first being discovered only in 1954, is also primarily used in the Western Amazon and the Orinoco Basin. But like yopo its pre-conquest range extended across much of South America and in the Carribbean. Related to nutmeg, over a dozen species are shamanically important for diagnosing illness and disease.
The methods of preparation vary but typically involve a process where the resin is scraped from the inner bark, dried, pulverized and mixed with lime ash. The psychoactive effects come from the copious trytamines and beta-carboline alkaloids available, most notably DMT, 5MEO-DMT and NMT. The effects can vary but initial excitability is followed by limb numbness, inability to control motor movements and intensely colorful and lively visuals.
Interestingly, the case with epená is such that it remains one of the few examples of psychedelic materials being incorporated into both the sacred entheogenic space and the profane. In parts of Coloumbia, the Indians not only use it shamanically but as a part of regular daily life. One can imagne that growing up in such a society would leave one's mental constituencies quite solid. Individuals within virola-using societies have an uncanny ability to see a tree and know as to its potency and effect. And the state of Western research is such that we know nothing about how this is understood, although the natives suggest the plants pass along the information. And with Amazonian socities continuing to disappear faster than we can learn about them, it seems plausible the knowledge will be lost.